Machinist&#39;s clamp



Nov. 1 1949 s. A PLACA MACHINIST'S CLAMP Filed Dec. 5, @947lll-Illllllllllllllllll4 JNVENTOR aPZa ca Ya lzmiar'e L BY fi r wwmm anA TT'ORNE )1 I Patented Nov. 1, 1949 UNITED STATES PATENT OFFICEMACHINISTS CLAMP Salvatore La Placa, Bridgeport, Conn.

Application December 5, 1947, Serial No. 789,871

Claims. 1

This invention relates to clamps, and more particularly to machinistsclamps of the type used to secure work to the table of a machine toolsuch as a planer, shaper, milling machine and the like.

Clamps of the above type generally comprise an arm or bar which isslotted intermediate its ends for receiving a bolt, by which the arm issecured to and over the table of a machine in spaced relation therewith.The machine table usually has T-slots for receiving the head of thebolt, and the bar in some instances has shoes or feet pivotally carriedat its ends;

An object of the present invention is to provide an improved clamp ofthe above type, which has considerable universality in its applicationwhereby it may be used to securely and adequate-- 1y hold a largevariety of difierent sizes and shapes of workpieces with greatreliability.

A further object of the invention is to provide an improved clamp asabove, in which the pressures exerted by a pad or foot at differentpoints thereon may be varied at will, to render the holding action ofthe foot, and of the clamp, more efiectiv'e.

Still another object of the invention is to provide an improvedmachinists clamp having pivotally movable feet, wherein greater clampingpressures may be applied to a workpiece at points inwardly removed fromthe edge of the piece, thereby resulting in a more secure clamping ofthe piece if for example it should have a rounded edge.

A still further object of the invention is to provide an improvedbar-type machinists clamp wherein the bar may be maintained more nearlyparallel to the worktable under various conditions of use, withoutrequiring the use of separate supplementary blocks, thereby saving timein the application of the clamp and insuring that a more positive andeffective clamping action is had.

One specific embodiment of the invention illus trated herein, by whichthese objects are accomplished, includes a clamping bar and manuallyadjustable means engageable with the bar at a point intermediate itsends for securing the bar to a worktable in difiere'ntly spacedpositions, and includes an adjusting screw threaded into and passingthrough one end of the bar, having a ball-and sock-et connection with apad or foot. By this organization the foot, which is pivotally carriedby the screw, may be spaced either closer or further away from the bar,and the adjustmerit made to suit any particular workpiece whereby thebar will be held relatively flat with respect to the worktable, withoutthe use of separate blocks, thereby to enable the full effectiveness ofthe clamp to be conveniently utilized at all times.

The other end of the bar pivotally carries a second foot which at apoint removed from its center is connected to the bar, the connectionbeing located closely adjacent the outer edge of the foot. Thus thepressure transmitted to the foot is so distributed that the said outeredge applies the greatest pressure on the work, and this edge may engagethe work at points inwardly removed from the edge of the work, resultingin a more secure clamping of the work where the latter has rounded edgesor flanges.

An adjustment screw is threaded into, and passes through the said otherend of the bar, the end of the screw bearing on the pivoted foot andenabling the ahg'ularity of the foot to be altered with respect to thebar, and thus the pressure applied by the foot at different pointsthereon may be varied whereby all pressures may be made equal, orunequal in diiferent degrees, to

achieve the most effective clamping action for each difierent workpiece.

In another embodiment of the invention both ends of the clamping barhaving pivoted feet, and adjusting screws for varying the angularity ofthe feet to suit different shapes and configurations of the workpieces.Thus, by the provision of the movably-mounted feet and adjustable meanswhereby the positioning of the feet with respect to the bar may becontrolled, a clamp is produced which is of universal use andapplication.

Other features and advantages will hereinafter appear:

In the accompanying drawings:

Figure 1 is a side elevational view of a clamp illustrating oneembodiment of the invention, mounted on a worktable and holding aworkpiece thereto.

Fig. 2 is a top or plan view of the clamp, worktable and workpiece ofFig, 1, and

Fig. 3 is a side elevational view of a clamp illustrating anotherembodiment of the invention.

The improved machinists clamp of the invention as shown in Figs. 1 and 2comprises an arm or bar Hi having a slot I I extending longitudinallythereof and located substantially midway be tween the ends I2 and I3 ofthe bar. A bolt l4 passes through the slot H, the head [5 of the boltbeing carried in a T-slot [6 in a worktable I! of a machine tool such asa milling machine, planer, or the like.

The upper surface of the bar It) is provided with a groove l8 having aconcave bottom surface as shown in Fig. 1, the groove accommodating aplate l9 having a convex undersurface 2i] engaging and conforming to thebottom of the groove. The plate [9 has a hole to enable the bolt I4 topass through it, the upper end of the bolt carrying a washer 2| and nut22 by means of which the bar l may be forced downward toward theworktable I! and held thereon.

In accordance with the present invention the end l2 of the bar ID hasthreaded in it and pass-- ing through it an adjusting screw 23 which maybe of the headless Allen type, the lower end of the screw having a ball24 which is received in a socket 25 of a shoe or foot 26. The ball 24 isretained in the socket 25 by means of a pair of locking plates 2'!secured to the upper surface of the foot 26 by screws as shown, the footthereby having a universal mounting on the adjustment screw 23.

Preferabl the undersurface of the foot 26 is provided with a hollow ordepression 28, to produce a pair of pressure surfaces or pads 29extending along opposite sides of the foot, the pads 29 being preferablyknurled as shown.

The other end 13 of the bar Ill has a pair of circular recesses 30 inits underside and on opposite sides of a central depending tongue 3|,which latter is apertured to receive a pivot bolt 32. A foot 33 ispivotally carried b the bolt 32, the foot having upstanding lugs 34which are apertured to receive the shank of the bolt, as

shown. The underside of the foot 33 has a hollow 35 providing a pair ofpads 36 and 31 which are preferably knurled.

In accordance with the invention the lugs 34 of the foot 33 are locatedclosely adjacent the outermost edge 38 of the foot, whereby a greaterportion of the pressure applied to the foot 33 by the bar I!) istransmitted by the outermost pad 31, and only a lesser portion isapplied by the innermost pad 36. Also, according to the invention, anadjusting screw 39 is threaded into and passes through the bar l0adjacent the end 13 thereof, the lower end of the screw 39 engaging theupper surface of the foot 33.

The clamping device shown in Figs. 1 and 2 is positioned to clamp aworkpiece 43 to the work! table H, the workpiece being engaged by thefoot 26 of the clamp, and the worktable being engaged by the foot 33 ofthe clamp. Such an arrangement may be advantageously used where theworkpiece is relatively thin; however, if the workpiece has considerablethickness, it may be engaged by and held under the clamping foot 33, andthe clamping foot 26 may be used to engage the worktable H. For thislatter arrangement it may be found that the bar [0 is tilted at quite anangle with respect to the worktable I! instead of being substantiallyparallel therewith. This condition may be easily rectified, to secure amore reliable and firmer clamping action, by adjustment of the screw 23.For example, the screw 23 may be threaded downward through the bar In toa considerable extent, thereby separating the foot 26 a substantialdistance from the underside of the bar. This will result in the barbecoming more nearly parallel to the surface of the worktable l l, andwill enable a more effective clamping of the workpiece to be had.

Also, it may be found desirable to equalize the pressures of the pads 36and 31 of the foot 33 on the workpiece, or on the worktable as the casemay be, and this may be readily accomplished by adjusting the screw 39so as to cause it to bear on the foot 33 with a moderate amount ofpressure. This also results in the clamp having a firmer mounting on theworktable H and lessens the likelihood of slippage of the clamp. In someinstances it ma be found desirable, in order to more securely hold aworkpiece, to increase the pressures of the pad 36 over the pressure ofthe pad 31, and this may be done by adjusting the screw 39, or if thescrew 39 is loosened or made to bear only lightly on the foot 33 thepressure of the pad 31 will be much greater than the pressure of the pad36, since the latter pad is further removed from the pivot screw 32 andtherefore has less force transmitted to it.

The clamp shown in Fig. 3 illustrates a modification of the invention.This clamp comprises an arm or bar 4| having a longitudinally extending,centralized slot 42 for receiving the drawbolt I4, the ends 33 and 44 ofthe bar pivotally mount ing feet 45 and 48 respectively in the samemanner that the foot 33 is mounted on the end l3 of the bar H] of Figs.1 and 2. The bar 43 has a pair of adjustment screws 41 which arethreaded into it and bear on the upper surfaces of the feet 45 and -46,the screws 41 controlling theangularity of the feet with respect to thebar 4|. Either one of the feet 45, 46 ma be made to engage a workpieceand the other one madeto engage the worktable, and the relativepressures of the knurled pads of the feet 45 and 46 may be adjusted tosecure the most efiective clamping action, by adjustment of the screws4?.

Variations and modifications may be made within the scope of thisinvention and portions of the improvements may be used without others.-

I claim:

1. A machinists clamp comprising a bar;

means engageable with the bar at a point inter-- mediate its ends forsecuring the bar to a work.

table; a pair of feet, one of said feet having workengaging surfaces atits ends; means for pivotally-- mounting said one foot at an off-centerpoint on one end of the bar; a screw threaded into and passing throughsaid end of the bar, said screw being engageable with said one foot tocontrol the angularity of the foot with respect to the bar,-

thereby to equalize the pressure exerted by the work-engaging surfacesof the foot; a secondscrew, threaded into and passing through the otherend of the bar; and a ball-and-socket con-- nection between the secondscrew and the other foot, said second screw enabling the other foot tobe positioned closer or further away from the bar.

2. A machinists clamp comprising a bar; means engageable with the bar ata point inter-- mediate its ends for securing the bar to a Work table; apair of feet, each having work-engaging surfaces at its ends; means forpivotally mount-' ing said feet at off-center points respectively on theends of the bar; and screws threaded into and" passing through said endsof the bar, said screwsbeing engageable with the feet to control theangularity thereof with respect to the bar, there-- by to equalize thepressure exerted by the work-'- engaging surfaces of the feet.

3. A machinists clamp comprising a bar;

means engageable with the bar at a point inter-- mediate its ends forsecuring the bar to a work table;' a foot having work-engaging surfacesat its ends, pivotally secured at an oif-center point to one end of thebar; and .adjustablemeans for controlling the angularity of said footwith respect to the bar, thereby to equalize the pressure exerted by thework-engaging surfaces of the foot.

4. A machinists clamp comprising a bar having means at its ends forengagement with machine parts and workpieces to be clamped, said barhaving a longitudinal slot extending through it intermediate its ends,having a recess in one face between said ends, said recess having aconcave bottom curved longitudinally of the bar and extending along saidslot on opposite sides thereof, and said bar having straight,longitudinal ribs on opposite sides of said recess and coextensivetherewith to reinforce and strengthen the :bar; an apertured bearingplate in said recess, having a comvex face engaging the concave bottomof the recess whereby the plate is slida'ble in the recess to differentangular positions and locations, said plate being interposed between thesaid ribs and having straight sides engaging the ribs to prevent turningof the plate; and a threaded draw bolt passing through the slot in thebar and through the aperture in the bearing plate, said bolt beingadapted to apply pressure to the said plate whereby the bar may beclamped in difierent angular positions over workpieces located on themachine part.

5. A machinists clamp comprising a bar having means at its ends forengagement with machine parts and workpieces to be clamped, said barhaving a longitudinal slot extending through it intermediate its endsand having a recess in one face between said ends, said recess having aconcave bottom curved longitudinally of the bar and extending along saidslot on opposite sides thereof; an apertured bearing plate in saidrecess, having a pair of straight, opposite edges, and having a convexface engaging the concave bottom of the recess whereby the plate isslidable in the recess to different angular positions and locations;means on said bar, extending along opposite sides of said recess andengaging the straight edges of the bearing plate, for simultaneouslyreinforcing said bar and holding said plate against turning; and a drawbolt passing through the slot in the bar and through the aperture in thebearing plate, said bolt being adapted to apply pressure to the saidplate whereby the bar may be clamped in different angular positions overworkpieces located on the machine part.

SALVATORE LA PLACA.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,346,504 Mathison July 13, 19201,490,063 Tower Apr. 8, 1924 1,676,289 Schmalz July 10, 1928 2,371,435Galorneau Mar. 13, 1945 FOREIGN PATENTS Number Country Date 111,832Switzerland Sept. 24, 1924 570,518 Great Britain July 10, 1945

